/**
 * Copyright The Apache Software Foundation
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with this
 * work for additional information regarding copyright ownership. The ASF
 * licenses this file to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package org.apache.hadoop.hbase.client;

import static org.apache.hadoop.hbase.client.ConnectionUtils.noMoreResultsForReverseScan;

import java.io.IOException;
import java.util.concurrent.ExecutorService;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.TableName;
import org.apache.yetus.audience.InterfaceAudience;
import org.apache.hadoop.hbase.ipc.RpcControllerFactory;

/**
 * A reversed client scanner which support backward scanning
 */
@InterfaceAudience.Private
public class ReversedClientScanner extends ClientScanner {

    /**
     * Create a new ReversibleClientScanner for the specified table Note that the passed
     * {@link Scan}'s start row maybe changed.
     *
     * @param conf
     * @param scan
     * @param tableName
     * @param connection
     * @param pool
     * @param primaryOperationTimeout
     * @throws IOException
     */
    public ReversedClientScanner(Configuration conf, Scan scan, TableName tableName, ClusterConnection connection,
            RpcRetryingCallerFactory rpcFactory, RpcControllerFactory controllerFactory, ExecutorService pool,
            int primaryOperationTimeout) throws IOException {
        super(conf, scan, tableName, connection, rpcFactory, controllerFactory, pool, primaryOperationTimeout);
    }

    @Override
    protected boolean setNewStartKey() {
        if(noMoreResultsForReverseScan(scan, currentRegion)) {
            return false;
        }
        scan.withStartRow(currentRegion.getStartKey(), false);
        return true;
    }

    @Override
    protected ReversedScannerCallable createScannerCallable() {
        return new ReversedScannerCallable(getConnection(), getTable(), scan, this.scanMetrics, this.rpcControllerFactory);
    }
}
